docs: def get_setting(self, name):
          notfound = object()
          "get configuration from 'constance.config' first "
          value = getattr(config, name, notfound)
          if name.endswith('_WHITELISTED_DOMAINS'):
              if value:
                  return value.split(',')
              else:
                  return []
  
          if value is notfound:
              value = getattr(settings, name)
          # Force text on URL named settings that are instance of Promise
          if name.endswith('_URL'):
              if isinstance(value, Promise):
                  value = force_text(value)
              value = resolve_url(value)
          return value